.app {
    font-family: Arial, sans-serif;
}

.mark_nav {
    position: relative;
    overflow: hidden;
    width: 100%;
}

.mark_nav ul {
    display: flex;
    padding: 0;
    margin: 0;
    list-style: none;
    transition: scroll 0.3s ease;
}

.mark_nav li {
    padding: 10px;
    cursor: pointer;
}

.mark_nav li.highlight {
    background-color: #f0f0f0;
    border: 2px solid orange;
    color: orange;
}

.jian_left, .jian_right {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background-color: #007bff;
    color: #fff;
    border: none;
    padding: 10px;
    cursor: pointer;
}

.jian_left {
    left: -20px;
}

.jian_right {
    right: -10px;
}

.mark_img {
    margin-top: 20px;
}

.mark_img img {
    max-width: 100%;
    height: auto;
}